The present invention relates to a semiconductor device and a method of manufacturing the same, particularly to a technique effective when applied to a semiconductor device having an interconnect containing a main conductor film having copper as a main component.
An inlaid interconnect structure is formed by embedding an interconnect material in an interconnect opening such as groove or recess formed in an insulating film by a metallization fabrication technique called damascene technique (single damascene or dual damascene technique). When a main interconnect material is copper (Cu), however, it tends to be diffused in an insulating film compared with a metal such as aluminum (Al) so that diffusion of copper in an inlaid interconnect into an insulating film is suppressed or prevented by covering the surfaces (bottom and side surfaces) of the inlaid interconnect with a thin barrier metal film in order to avoid direct contact of the inlaid interconnect made of copper with the insulating film. In addition, by forming an interconnect cap barrier insulating film made of, for example, a silicon nitride film, and covering therewith the upper surface of the inlaid interconnect, diffusion of copper in the inlaid interconnect into the insulating film from the upper surface of the inlaid interconnect is suppressed or prevented.
In recent years, such inlaid interconnects are narrowly spaced, reflecting an increase in the integration density of a semiconductor device. This increases the parasitic capacitance between interconnects and causes signal delay, which forms cross talk between two adjacent interconnects. A reduction in the parasitic capacitance between interconnects is therefore desired. For reducing the parasitic capacitance between interconnects, low dielectric constant materials are used for an interlayer dielectric film. For example, disclosed in Japanese Patent Application Laid-Open No. 2001-85519 is a technique of forming interconnects to have a reverse taper shape and forming an interlayer dielectric film to form an air gap in the space between these interconnects. This air gap is formed to reduce the interconnect capacitance.